Topic: Smoothbore vs Rifling

Somebody help me out here. Numberous tech specifications for tanks list Smoothbore for the main gun. To my brain, that means Non-Rifled, thusly the fired round does not spin and is less accurate over long distances and loses the bonus of spin at impact. But so many modern tanks list Smoothbore, I think I'm missing something.

Can anyone shed some light on this for me?

October 1st, 2004

SHERMAN

Like I siad, you loose muzzle-valocity with the Rifled guns....The older guns(105mm) mostly were rifled, but I think they gave it up with the 120mm ammo being so powerfull anyways...Costs more to rifle..... The Russians had rifled guns 2(as I know) up to the 115mm which was a smooth bore. The brits used a 120mm rifled on the Chieftain NBT, making it the first western tank with a 120mm, and continued using the Rifled 120mm on Challenger I and II.

October 1st, 2004

doddsy2978

The smoothbore (non rifled) 120mm barrels are used to fire APFSDS rounds. These are Armour Piercing Fin Stabilized Discarded Sabot rounds. The spin is, obviously, imparted by the fins. The Sabot is the waste of the shot that makes the round 'bullet' shaped for firing and is discarded soon after the round has left the muzzle. This leaves the round looking like a large dart. It is inert and its power is in the energy that the round has - it is made from depleted uranium. This is the round that has recently caused some controversy.

Oh! To my knowledge - the Challenger is fitted with a 120mm smoothbore gun and fires the APFSDS round.

--

October 2nd, 2004

godofthunder9010

Quote:

Originally Posted by SHERMAN

Like I siad, you loose muzzle-valocity with the Rifled guns....The older guns(105mm) mostly were rifled, but I think they gave it up with the 120mm ammo being so powerfull anyways...Costs more to rifle..... The Russians had rifled guns 2(as I know) up to the 115mm which was a smooth bore. The brits used a 120mm rifled on the Chieftain NBT, making it the first western tank with a 120mm, and continued using the Rifled 120mm on Challenger I and II.

I remember your response Sherman and I appreciate it. I just want to get as much data, both for and against. Since the Brits are doing it, I assume there is a good reason to rifle the barrel of the main gun.

October 2nd, 2004

SHERMAN

Well, I think they just kept it from the Chieftain....I think that when they were first with the 120mm(Chieftain) they kind of got fixated with the rifling, while the other MBT makers had time to think it over...When the Challenger I came out it got baiscally the same L11 120mm rifled main gun as the Chieftain...So, when they had to decide what to do for a main gun for the Challenger II, someone probably stood up and said "We already got a rifled 120mm, and our other tanks have it...We might as well improve it a bit and stick it on..."
They now wish to develope a Smooth-Bore to replace it:

Quote:

Challenger 2 is equipped with an L30, 120mm rifled tank gun from BAE Systems RO Defence. In January 2004, RO Defence was awarded a contract to develop a new smoothbore 120mm gun for the British Army Challenger tanks. A technical demonstrator will be produced by 2006.

Do you know what the life of a Chieftain barrel is, Sherman? It is not long about 200 round equivalents, if memory serves (somebody can correct me here). Smoothbore barrels last longer because the metal of the barrel is less likely to migrate towards the muzzle. This is what limits the life of the rifled barrel (120mm AP rounds are quite heavy).

This migration causes a narrowing of the bore at the muzzle end of the barrel, which will eventaully prevent the passage of the round. This would have a catastrophic effect on the barrel and, probably, the crew.

I was sure that the Challenger is fitted with a smoothbore and will check. I have definitely seen APFSDS ammunition though and due to the mass of the round (have you ever pick one up?) - would doubt it being fired through a rifled barrel (exasperate the migration problem). My point is - there must be some smoothbore barrels out there in the British Army and the only logical place is in the turret of a tank. The only MBT we have is Challenger - QED!

Ok! I have read your page and all I can say is 'That is bloody typical of our Gov's attitude' I would be interested to learn what the life of the barrel is though. As an aside did you know that in theory, you could own a tank with a smoothbore gun on a shotgun licence. I say 'in theory'!

October 2nd, 2004

SHERMAN

LOL@Shotgun....

As to the Life span of a rifled weapon, that is true.....Did not consider that up to now...That would explain the move to smooth bore guns as the ammo is getting more and more powerfull, causing more tear and wear on the barrel. But, you should think about this: The UK came up with the Centurion, and after coupeling it with the L7 Rifled 105, had what was arguably the best tank in the world at that time. Than they came up wih the Chieftain, and again with a 120mm gun had what was(with all its little problems) argaubly the best tank in world. So, why souldent they go with the rifled...It was the natural thing to do.....All that into consideration, the brits again can claim that they have the best tank in world....Even if the Germans, Americans and Israelis will get mad.

October 2nd, 2004

Animal Mother

The Challenger series do indeed use a rifled gun. Reason why they can still use HESH, which require spin to work properly.

October 3rd, 2004

godofthunder9010

So what is the consensus then? If the rifled barrel on British tanks a significant drawback or a significant advantage? Do they lose range with the loss of muzzle velocity, or does the spin compensate for this?